Case Report: Re-evaluating Reversibility of Cytotoxic Lesions of the Corpus Callosum

Victoria Vold ¹ Stein-Helge Hansen Tingvoll ^2,3 Mona Kristiansen Beyer ^1,4 Kaja Nordengen ^1,5*

• ¹ Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
• ² Department of Neurology, Lillehammer Hospital, Lillehammer, Norway, Lillehammer, Oppland, Norway
• ³ Ringen Rehabilitation Centre, Moelv, Norway
• ⁴ Division of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway
• ⁵ Department of Neurology, Oslo University Hospital, Oslo, Oslo, Norway

Cytotoxic lesions of the corpus callosum (CLOCC) are a clinicoradiological diagnosis, characterized by transient neurological symptoms and magnetic resonance imaging (MRI) changes in the splenium of the corpus callosum (SCC), which in most cases is completely reversible. However, the long-term pathophysiological trajectory and ultimate neurological outcomes of CLOCC remain largely unknown due to limited long-term follow-up data. We report an 11-year follow-up of a postpartum female with CLOCC, initially presenting with transient focal neurological symptoms and extensive diffusion-restricted white matter involvement including the SCC and surrounding area with diffusion restriction and low apparent diffusion coefficient values, indicative of cytotoxic edema. The edema regressed in days; over the years, she remained asymptomatic despite persistent white matter changes on MRI in the centrum semiovale. This case challenges the view of CLOCC as completely reversible and raises questions regarding the significance of lasting white matter changes. The enduring absence of neurological symptoms and stable radiological profile throughout the decade underscores the singular nature of CLOCC and the lasting, though isolated, impact on white matter. This report contributes a crucial perspective, suggesting that CLOCC may involve just an isolated episode without recurrent events or progressive neurological decline.By offering the first longitudinal analysis of a CLOCC episode with an extended follow-up of over a decade, our case enhances current knowledge about the long-term neurological and radiological landscape of this condition. It suggests a reevaluation of the conceptual understanding of CLOCC as an entirely reversible, non-relapsing disorder, highlighting the need for further research into its long-term impacts on cerebral white matter integrity.